John Nolan/Times photo
WMUR weatherman Kevin Skarupa was a hit with School Street School students, recently.

ROCHESTER — For some people, the technical aspects of weather forecasting may be a dry subject, but Kevin Skarupa, Channel 9’s morning meteorologist, with his sunny smile and infectious enthusiasm, was able to make the topic engrossing for School Street School students, during a recent visit.

He held the attention of dozens of youngsters for well over half an hour, with a visual presentation and a fact-packed talk. This included details of his forecasting tools of the trade — six computers, and the occasional glance outside — plus a rundown of weather features that can impact this region.

Skarupa described the information provided by each of the computers in the TV station’s weather room — one is able to provide 200 maps per hour providing meteorological details from all over the world.

“Half of them are wrong, and it is up to us to make our predictions,” said Skarupa, who starts absorbing all this information in the office at around 2 a.m. each morning, in readiness for his first appearance on screen just a few hours later.

He told the students there are 50 different cloud types (but didn’t complicate matters further by mentioning Undulus Asperatus, which the Cloud Appreciation Society is lobbying for as an additional species).

Skarupa described the differences between the most common clouds — cumulus, stratus, nimbus and cirrus — and what might be expected when they are in the sky. He went on to describe the evaporation-precipitation water cycle, and noted that forecasters have to predict when precipitation will arrive, how long it will last, how much will fall, and if it be in the form of rain, hail, sleet, ice storm or snow.

“Nor’easters are very difficult to predict — they can switch to rain,” he told the students.

He went on to talk about thunderstorms and major rain events leading to flooding, and recalled back in October 2005, western New Hampshire was doused with 18 inches of rain in two days. Skarupa, noting the danger of lightning, which is attracted by tall objects, metal and water, warned the youngsters to shelter inside if it approaches.

He explained how hailstones are formed — they usually only reach a maximum of golf ball size in New Hampshire — and asked the students what is needed to form a rainbow. Sun and rain, they responded, and he reminded them that they can achieve the same effect with a garden hose.

Tornadoes were up next, and Skarupa recalled that four years ago one touched down in New Hampshire and was on the ground for 50 miles.

“It took two and a half days to assess the damage,” he said.

Next, Skarupa showed a slide of a weather station and briefly mentioned some of the instruments assembled there — a thermometer to record the temperature, an anemometer to measure wind speed, a barometer to gauge the atmospheric pressure and a hygrometer to ascertain the moisture content in the environment. He also explained the presence of a plastic owl among the instruments — to deter the presence of other birds whose droppings might distort readings, particularly in the rain gauge.

At the end of the presentation, the weatherman asked if anyone had questions.

Kindergartner Hayley Peace-McClelland asked, “How do you make rain?” After Skarupa explained the formation and content of clouds, and what triggers rain from them, he said that sometimes clouds travel great distances before releasing their content. He gave as an example, storm clouds coming over the Atlantic all the way from Africa, and, over Florida, releasing rain that contained copious amounts of Saharan sand grains.

Skarupa detailed the most common scenarios (tornadic cells embedded in severe thunderstorms) and the conditions required to trigger them. He also mentioned small versions of tornadoes common in desert areas, known as dust devils, and their Australian equivalent, willy-willies.

At the conclusion of his program, Skarupa took out a hand-held camera, panned around the room as students waved enthusiastically, and told them they would appear on his Channel 9 TV segment the following morning.